Many who were in the crowd complained of being charged by police on horseback.

Police have denied that mounted officers charged at protesters; however, a five-minute video posted on YouTube last night shows a number of officers on horseback advancing at speed through a crowd of people.

Jenny Love, 22, who graduated from Bath University in July, said mounted officers "charged without warning".

"When the horses charged I was fairly near the front of the demo, where we were very tightly packed in, and found myself very quickly on the floor where I assumed the foetal position and covered my head while people simply ran over me," she said.

"Thankfully another protester picked me up before I could suffer any serious damage."

Love described the charge "as pretty terrifying" and said she suffered bruising during the ordeal. "I'm very angry that the mounted police were ordered to charge on a crowd containing many people like me who were only interested in peaceful protest," she said. "Police chiefs should think themselves lucky that no one was more seriously injured."

Naomi Bain, a member of support staff at Birkbeck University, was at Whitehall on Wednesday to protest against the government cuts. She said: "We were right at the front of the crowd. I've been in a lot of protests before, so we weren't particularly scared of police shouting at us and telling us to move. We were standing our ground – until the horse charge.

"I don't think I've ever seen anything quite so frightening. I've seen police on horseback, but this was like a cavalry charge. There was a line of police on foot, and they just moved out of the way, then maybe a hundred yards down the street there was a line of police on horseback. We'd been standing firmly and just moving back slowly, but when the police on horseback charged, that was the moment when we absolutely ran."

Bain said she was standing with school and college pupils, some as young as 15, when mounted police advanced. "There were people who fell down who would have been under the horses' hooves if they hadn't been grabbed – and these were really young kids as well."

Jonathan Warren, a freelance photojournalist who was at the protest, said mounted police advanced "with no warning". "There was a line of police officers, which parted, and then the police on horseback just started charging," he said, adding that protesters were left "angry and scared".

Archie Young, 18, who was protesting with his mother, Josa, said he was left bruised following the charges. "I was at the forefront of the crowd of protesters that they charged, yes – my left boot still has a hoofprint-shaped mark on it from where I was trodden on," he said.

Yesterday a spokesman for the Metropolitan police said: "Police horses were involved in the operation, but that did not involve charging the crowd." He added: "I dare say they [officers policing the Whitehall demonstrations] were doing the movements the horses do to help control the crowd for everyone's benefit, which has been a recognised tactic for many, many years, but no, police officers charging the crowd – we would say, 'No, they did not charge the crowd.'"

However the spokesman did also say that charging was a "quite specific term". His rebuttal came after the Metropolitan police commissioner, Sir Paul Stephenson, told a Metropolitan police authority meeting he had "no reference" to police officers on horseback charging at protesters.

The Guardian witnessed a charge by police mounted on about 10 horses shortly after 7pm on Wednesday near Trafalgar Square. The incident occurred when about 1,000 protesters had gathered outside the kettle to call for those inside to be released. Some began hurling missiles and surging forward.

In a co-ordinated move, the riot officers, who numbered about 100, simultaneously retreated to the sides of the street, allowing the horses to come forward approximately 100 metres. Panic spread through the crowd as protesters sprinted away. Witnesses said it was the second time police had charged with horses in the space of an hour, with unconfirmed reports of a young man having been trampled.